Battery pack lockable with a cordless power tool

ABSTRACT

A battery pack with a device for locking said battery pack to a cordless power tool has a guide configured to guide the battery pack in a predetermined movement direction as it moves between a locking position in which it is locked to the cordless power tool and a removal position in which it is removed from the cordless power tool, the guide has a break in at least one location between the locking position and removal position, and at said location a force acting on the battery pack moves the battery pack into a safety position offset from the guide, in which the battery pack is prevented from moving further along the guide into the removal position.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority of U.S. patentapplication Ser. No. 11/220,107 filed Sep. 6, 2005 under 35 USC 119(e).The subject matter of the aforesaid U.S. patent application isexplicitly incorporated herein by reference thereto.

The invention described and claimed hereinbelow is also described inGerman Patent Application DE 10 2004 044 331.9 filed on Sep. 9, 2004.This German Patent Application provides the basis for a claim ofpriority of invention under 35 U.S.C. 119(a)-(d).

BACKGROUND OF THE INVENTION

The present invention relates to a battery pack lockable to a cordlesspower tool by a locking device.

Locking devices of this type are used, for example, to reliably connectcordless hand-guided power tools to a battery pack used as a powersupply.

The known locking devices usually have a linear guide provided on thepower tool into which the battery pack is slid until, after being slidall the way in, it comes into contact with a stop and is locked in thisposition in relation to the power tool, while simultaneously producingan electrical connection between a battery of the battery pack and anelectrical circuit of a consumer of the power tool. The locking usuallyoccurs with the aid of a latch, which is supported in a housing of thepower tool so that it can move in opposition to the force of a springand which the spring force brings into engagement with a detent recessin the battery pack. A release mechanism is used to release theconnection and usually has a push button, which is situated in theregion of the guide and is manually actuated in order to disengage thelatch from the detent recess and release the battery pack. The batterypack is then slid along the guide into a removal position in which it nolonger engages the cordless power tool.

Since the movement resistance while the battery pack is being slid intothe guide of the power tool generally increases toward the end of theinsertion path due to the increasing size of the friction surfaces anddue to the contact between the electrical terminals, the user can begiven the impression that the two components are properly locked inposition although this is not yet the case. This can result in thebattery pack slipping out of the guide during transport or operation ofthe power tool when the latter is tilted downward toward the removalposition, which can lead to property damage or injury.

In order to prevent the battery pack from unintentionally detaching fromthe power tool, some of the applicant's larger and heavier power toolsare already provided with a two-stage locking device called a doublelocking mechanism in which, as the battery pack is slid into the guide,the spring force of a spring-loaded latch brings it into engagement withtwo detent recesses provided in the battery pack, one after the other inthe insertion direction. When the latch engages with the first detentrecess, the battery pack is only secured in relation to the power tool,whereas an electrical connection is only produced when the latch engagesin the second detent recess.

This does make it possible to prevent the battery pack fromunintentionally detaching from the power tool when the latch is notengaging in the second detent recess or is not properly engaging in it,for example because the user has not slid the battery pack all the wayinto the locking position in the guide. But if the user does not holdthe battery pack while actuating the release mechanism and the guide issimultaneously pointing obliquely downward from the locking position,then even a two-stage locking mechanism is unable to reliably preventthe battery pack from falling out.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide abattery pack and a cordless power tool lockable with one another, whichavoid the disadvantages of the prior art.

In keeping with these objects and with others which will become apparenthereinafter, one feature of the present invention resides, brieflystated, in a battery pack comprising a device for locking said batterypack to a cordless power tool, comprising a guide configured to guidethe battery pack in a predetermined movement direction as it movesbetween a locking position in which it is locked to the cordless powertool and a removal position in which it is removed from the cordlesspower tool, said guide having a break in at least one location betweenthe locking position and removal position, and at said location a forceacting on the battery pack moves the battery pack into a safety positionoffset from said guide, in which the battery pack is prevented frommoving further along said guide into the removal position.

Another feature of the present invention resides in a cordless powertool comprising a device for locking said cordless power tool to abattery pack, comprising a guide configured to guide the battery pack ina predetermined movement direction as it moves between a lockingposition in which it is locked to said cordless power tool and a removalposition in which it is removed from said cordless power tool, saidguide having a break in at least one location between the lockingposition and removal position, and at said location a force acting onthe battery pack moves the battery pack into a safety position offsetfrom said guide, in which the battery pack is prevented from movingfurther along said guide into the removal position.

When the battery pack and the cordless power tool are designed inaccordance with the present invention, it has the advantage over theprior art that in locking mechanisms with either a one-stage or atwo-stage locking action, the battery pack can be prevented fromuncontrollably dropping out of the guide if the user is not holding itor is not holding it correctly when the guide is tilted downward and therelease mechanism is intentionally or unintentionally actuated.

The present invention is based on the idea that the battery pack lockedto the power tool after being unlocked and while being moved along theguide out of the locking position and into the removal position, isforcibly deflected into a safety position offset from the guide by meansof the break in the guide and the force exerted at this location, and inthe safety position, the battery pack is secured in relation to thecordless power tool until the user grasps it and disengages it from thesafety position again, in opposition to the exerted force, in order tothen slide it along the guide until it travels all the way into theremoval position.

Since battery packs are usually removed while power tools are being heldin their normal operating position in which the battery pack is pointingdownward, the force acting on the battery pack can easily be exerted bythe weight of the battery pack if its center of gravity is lower in thesafety position than during its movement along the guide and gravityconsequently pulls the battery pack downward into the safety position.But since this orientation is not necessarily always maintained andcould also be different in other cordless power tools, in a preferredembodiment of the present invention, the force acting on the batterypack is a spring force that pushes or pulls the battery pack into thesafety position and has the advantage over gravity that it worksregardless of the spatial orientation of the components.

In another preferred embodiment of the present invention, the springacts on the battery pack essentially transversely to the movementdirection of the battery pack in the guide in order to move the batterypack directly and without deflection of the force direction, into thesafety position, in a direction transverse to its movement path in theguide. Even when a spring is used to generate the force required, it ispreferable for the safety position to be offset downward in relation tothe movement path of the battery pack in the guide in order to provide aredundancy by means of the battery pack's weight acting on it in thesame direction as the force of the spring during the movement of thebattery pack into the safety position.

Alternatively, however, the spring can also act on the battery packessentially in its movement direction in order, after the unlocking, toslide it along the guide in the direction of the removal position until,in the break region, the battery pack engages with a suitable guidesurface that moves the battery pack, through the action of the springforce and preferably also through the action of its weight, out of themovement path along the guide and into the safety position.

According to another preferred embodiment of the present invention, thecordless power tool and the battery pack are adapted to each other sothat in the safety position, the battery pack is in fact prevented frommoving toward the removal position, but is able to freely move in theopposite direction toward the locking position so that when beingattached to the cordless power tool, the battery pack can be movedfreely all the way into the locking position, even if it is moved intothe safety position in the meantime because the user is not holding itcorrectly. This is preferably achieved by means of the fact that thebattery pack and the cordless power tool are provided with cooperatingstop surfaces at one end and are provided with cooperating leadingbevels at the other; in the safety position, the stop surfaces aresituated opposite one another in the removal direction and prevent thebattery pack from being moved further toward the removal position, whilethe leading bevels are situated opposite from one another in the lockingdirection and cause the battery pack to be automatically pushed back outof the safety position when the force acting on it has moved it into thesafety position while it is being slid into the locking position.

In order to provide for a perceptible movement into the safety positionin the break region and to simultaneously provide an essentiallyplay-free guided relative movement between the battery pack and thecordless power tool in the guide both before and after the break, theguide on the battery pack and on the cordless power tool preferably hasalternating projections and recesses; in the region of the break, atleast part of the projections engage in the opposing recesses and beforeand after the break, the respective projections rest against one anotherwith opposing guide surfaces.

As in conventional locking mechanisms of power tools and battery packs,the guide is suitably embodied in the form of a linear guide that guidesthe battery pack on a straight movement path until the break in theguide, where the force exerted on the battery pack causes it to leavethe movement path and move into the safety position. Alternatively,however, the guide could also be embodied in the form of a curved guideso that the battery pack is attached to and detached from the cordlesspower tool, for example by means of a rotating motion; the safetyposition is suitably offset in relation to the rotation direction, inthe direction that the force is exerted.

The novel features which are considered as characteristic for thepresent invention are set forth in particular in the appended claims.the invention itself, however, both as to its construction and itsmethod of operation, together with additional objects and advantagesthereof, will be best understood from the following description ofspecific embodiments when read in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cutaway perspective view of a first embodimentform of a locking device for locking a power tool to a battery pack;

FIG. 2 is a cutaway view of the device from FIG. 1, cut along the planeII-II, which shows the battery pack in a locking position;

FIG. 3 is a view corresponding to FIG. 2, which shows the battery packduring removal from the power tool as it reaches a break in a guide ofthe locking device;

FIG. 4 is a view corresponding to FIG. 2, which shows the battery packin a subsequently assumed safety position;

FIG. 5 is a view corresponding to FIG. 2, which shows the battery packafter removal from the power tool, in a removal position;

FIG. 6 is an enlarged cutaway side view of a second embodiment form of alocking device for locking a power tool and a battery pack together,which shows the battery pack in the locking position, as depicted inFIG. 2;

FIG. 7 is a view corresponding to FIG. 6, which shows the battery packduring removal from the power tool as it reaches a break in a guide ofthe locking device;

FIG. 8 is a view corresponding to FIG. 6, which shows the battery packin a subsequently assumed safety position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The locking devices 2 shown in the drawings are used to lock a cordlesspower tool 4, for example a hand-guided percussion drill, to a batterypack 6 required to supply power to the power tool 4.

As best shown in FIGS. 1 through 5, on the free lower end of its handle8, the power tool 4 is provided in a known fashion with a protrudingguide rail 10 that can be slid in the direction of the arrow A into aguide groove 12 let into the upper end of the battery pack 6. This guidegroove 12 has a cross section complementary to the cross section of theguide rail 10 and, together with it, constitutes a linear guide thatdefines the predetermined insertion direction (arrow A).

The guide rail 10 is provided with two laterally protruding guide strips14, whose cross sections essentially correspond to the cross sections oftwo guide slots 16 (only one of which is visible in FIG. 1) situatedopposite from each other inside the guide groove 12. The tops of the twoguide strips 14 are each composed of three projections 18, 20, 22 withflush, flat tops situated one after the other in the longitudinaldirection, between which elongated recesses 94 and 26 are provided.

When the guide rail 10 is inserted into the guide groove 12, the twoguide strips 14 engage with the guide slots 16, whose upper limitsurfaces facing the tops of the guide strips 14 are provided with twoelongated recesses 28, 30 situated spaced apart from one another in thelongitudinal direction, while before, between, and after the recesses28, 30, the guide slots 16 extend parallel to the tops of theprojections 18, 20, 22 of the associated guide strips 14. The foremostprojection 18 of each guide strip 14 in the insertion direction is sizedso that it fits in the hindmost recess 28, while a protrusion 32 betweenthe recesses 28, 30 is sized so that it fits into the recess 24 betweenthe foremost projection 18 and the subsequent projection 20.

The insertion movement of the guide rail 10 into the guide groove 12 islimited by means of cooperating stops 34, 36 (see FIGS. 3 and 4), whichare situated at the rear ends of the guide rail 10 and guide groove 12in the insertion direction and rest against each other when the batterypack 6 is properly locked to the power tool 4 in its locking positiondepicted in FIG. 2 and an electrical connection is produced between theterminals of a storage battery of the battery pack 6 and an electricalcircuit of a consumer of the power tool 4.

As best shown in FIG. 1, the locking device 2, in an intrinsically knownmanner, has two latches 40 (only one of which is visible), which can bemoved in a spring-loaded fashion symmetrical to a vertical central planeof the guide rail 10, in a transversely extending latch guide and, withtheir opposing ends, protrude beyond adjacent lateral guide surfaces ofthe guide strips 14. When the battery pack 6 is locked to the power tool4, the end surfaces of the latches 14 each engage in opposing detentrecesses 38 (only one of which is visible) on the inside of the guidegroove 12 of the battery pack 6. In a likewise intrinsically knownmanner, the locking device 2 has a release mechanism (not shown), whichcan be manually actuated to disengage the latches 14 from the detentrecesses 38 in order to release the battery pack 6.

The locking device 2 can be designed for a one-stage or two-stagelocking action; in the latter case, two additional detent recesses (notshown) are provided before the detent recesses 38 in the insertiondirection in order to accommodate the latches to secure the battery pack6 to the power tool 4 without an electrical connection being producedbetween the terminals of the storage battery of the battery pack 6 andthe electrical circuit of the consumer of the power tool 4. Thisconnection is produced when the battery pack 6 reaches the positionshown in FIG. 2.

To prevent the battery pack 6 from sliding off of the guide rail 10 ifthe latter is tilted downward counter to the insertion direction (arrowA) and the release mechanism is intentionally or unintentionallyactuated without the battery pack 6 being grasped, the guide 10, 12 hasa break between the locking position and the removal position, whichmakes it possible to deflect the battery pack 6 out of its linearmovement path between the locking position shown in FIG. 2 and theremoval position shown in FIG. 5, transversely in relation to the guide10, 12, into a safety position shown in FIG. 4, in which it is preventedfrom moving further toward the removal position.

The break of the guide 10, 12 is situated at the point in the movementpath of the battery pack 6 at which the projections 18 and 20 on thetops of the guide strips 14 are situated opposite the recesses 28 and 30in the upper limit surfaces of the guide slots 16 and the protrusions 32in the upper limit surfaces of the guide slots 16 are situated oppositethe recesses 24 in the tops of the guide strips 14, as shown in FIG. 3.In this position, the weight of the battery pack 6 pulls it downward(arrow G), causing the projections 18 and 20 to engage in the recesses28 and 30 and the protrusions 32 to engage in the recesses 24.

At their rear ends in the insertion direction, the projections 18 havestop surfaces 42 that are perpendicular to the insertion direction and,in the safety position, are situated opposite complementary stopsurfaces 44 of the recesses 28 so that they prevent the battery pack 6from moving further toward the removal position, as shown in FIG. 4. Inorder to disengage the battery pack 6 from the safety position forremoval, it only needs to be lifted slightly in the direction of thearrow B and then moved again further in the guide 10, 12 until itreaches the removal position.

By contrast, at their front ends in the insertion direction, theprojections 18, 20, and 22 are bounded by leading bevels 46, 48, 50,which in the safety position, are situated opposite complementaryleading bevels 52, 54 of the recesses 28, 30. This allows the batterypack 6 to be slid unhindered into the locking position, even if it isnot held correctly by the user and moves into the safety position as aresult.

Whereas with the locking device 2 shown in FIGS. 1 through 5, themovement of the battery pack 6 into the safety position is initiated bythe force of gravity on it, with the locking device 2 shown in FIGS. 6through 8, two prestressed leaf springs 60 are also provided in order totilt the battery pack 6 in relation to the power tool 4, into the safetyposition shown in FIG. 8 when it reaches the break in the guide 10, 12(FIG. 7). The leaf springs 60 are inserted into the battery pack 6underneath the guide slots 16 so that they press from underneath againstthe underside of the adjacent guide strips 14 and press the adjacentguide surfaces 62, 64 of the guide groove 12 and guide rail 10 apartfrom each other when the break in the guide 10, 12 is reached. Theprojections 18 are brought into engagement with the recesses 28 and theprotrusions 32 are brought into engagement with the recesses 24 asdescribed above.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in adevice for locking an cordless power tool to an battery pack, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will reveal fully reveal thegist of the present invention that others can, by applying currentknowledge, readily adapt it for various applications without omittingfeatures that, from the standpoint of prior art, fairly constituteessential characteristics of the generic or specific aspects of theinvention.

1. A system comprising a battery pack, a cordless power tool, and adevice for locking said battery pack to said cordless power tool, thesystem comprising: a guide comprising a linear guide strip disposed onthe cordless power tool and a linear guide slot disposed on the batterypack, the guide strip being slidably received within the guide slot andconfigured to guide the battery pack in a predetermined longitudinalmovement direction as the battery pack moves between a locking positionin which the guide strip is locked within the guide slot to lock thebattery pack to the cordless power tool and a removal position in whichthe guide strip is removed from the guide slot to remove the batterypack from the cordless power tool; and at least one detent recessdisposed on the battery pack and at least one mating latch disposed onthe power tool, wherein in the locking position, the latch is broughtinto engagement with the detent recess to lock the battery pack to thecordless power tool, and wherein the latch in released from the detentrecess to allow the battery pack to be moved to the removal position;said guide further comprising a break formed by at least one transverseprojection or recess on or in the guide strip, respectively, in at leastone location along the longitudinal length of the guide strip, such thatwhen the battery pack moves from the locking position towards theremoval position, at said location a force acting on the battery packmoves the guide strip within the guide slot transversely to saidlongitudinal direction into a safety position, in which said projectionor recess in said guide strip engages a mating transverse recess orprojection in the guide slot such that the guide strip is prevented frommoving further along said guide slot into the removal position.
 2. Asystem as defined in claim 1, wherein the force acting on the batterypack in said location is a weight of the battery pack.
 3. A system asdefined in claim 1; and further comprising a spring arranged within saidguide slot so that the force acting on the battery pack is a force ofsaid spring.
 4. A system as defined in claim 3, wherein said spring isarranged so that the spring acts on said battery pack and on the powertool essentially transversely in relation to a movement direction of thebattery pack into the removal position.
 5. A system as defined in claim1; and further comprising stop surfaces provided within the guide slotof the battery pack and on the guide strip of the cordless power tool,situated opposite to one another in the safety position, and preventingthe battery pack from moving further into the removal position.
 6. Asystem as defined in claim 1; and further comprising leading bevelsprovided within the guide slot of the battery pack and on the guidestrip of the cordless power tool, situated opposite to one another insaid safety position, and permitting the battery pack to move into thelocking position.
 7. A cordless power tool comprising a device lockingsaid cordless power tool to a battery pack, said device comprising: aguide comprising a linear guide strip disposed on the cordless powertool and a linear guide slot disposed on the battery pack, the guidestrip being slidably received within the guide slot and configured toguide the battery pack in a predetermined longitudinal movementdirection as the battery pack moves between a locking position in whichthe guide strip is locked within the guide slot to lock the battery packto the cordless power tool and a removal position in which the guidestrip is removed from the guide slot to remove the battery pack from thecordless power tool; and at least one detent recess disposed on thebattery pack and at least one mating latch disposed on the power tool,wherein in the locking position, the latch is brought into engagementwith the detent recess to lock the battery pack to the cordless powertool, and wherein the latch in released from the detent recess to allowthe battery pack to be moved to the removal position; said guide furthercomprising a break formed by at least one transverse projection orrecess on or in the guide strip, respectively, in at least one locationalong the longitudinal length of the guide strip, such that when thebattery pack moves from the locking position towards the removalposition, at said location a force acting on the battery pack moves theguide strip within the guide slot transversely to said longitudinaldirection into a safety position, in which said projection or recess insaid guide strip engages a mating transverse recess or projection in theguide slot such that the guide strip is prevented from moving furtheralong said guide slot into the removal position.
 8. A cordless powertool as defined in claim 7, wherein the force acting on the battery packin said location is a weight of the battery pack.
 9. A cordless powertool as defined in claim 7; and further comprising a spring arrangedwithin said guide slot so that the force acting on the battery pack is aforce of said spring.
 10. A cordless power tool as defined in claim 9,wherein said spring is arranged so that the spring acts on said batterypack and on the power tool essentially transversely in relation to amovement direction of the battery pack into the removal position.
 11. Acordless power tool as defined in claim 7; and further comprising stopsurfaces provided within the guide slot of the battery pack and on theguide strip of the cordless power tool, situated opposite to one anotherin the safety position, and preventing the battery pack from movingfurther into the removal position.
 12. A cordless power tool as definedin claim 7; and further comprising leading bevels provided within theguide slot of the battery pack and on the guide strip of the cordlesspower tool and situated opposite to one another in said safety positionand permitting the battery pack to move into the locking position.